Общий каталог Yamawa 2022 - 2023 - страница 1164

Classes of Internal Threads and Classes of Taps Description of products 1. YAMAWA P Class System YAMAWA P Class system for thread limits is specified in accordance with JTA (The Japan Solid Cutting Tools’ Association). Pitch diameter tolerance zones for normal size M1〜M52 (U,W up to 2") are shown in the table below. Depending on pitch diameter tolerance and tolerance position, pitch diameter tolerance zones are classified into three types, A , B and C. (1) A type : 15μm tolerance. The tolerance of P1, P2, P3… is defined as basic +10〜+25μm, +25〜+40μm, +40〜+55μm and so on, respectively. (2) B type : 20μm tolerance. The tolerance of P1, P2, P3… is defined as basic +0〜+20μm, +20〜+40μm, +40〜+60μm and so on, respectively. (3) C type : 40μm tolerance. The tolerance of P2, P3, P4… is defined as basic +0〜+40μm, +20〜+60μm, +40〜+80μm and so on, respectively. YAMAWA P class system is made in a step form. It can be used to select depending on the tapping conditions. ■ Pitch Tolerance zone for P Class with Nominal size and Pitch Nominal Size 1mm≦Size≦24mm 24mm＜Size≦30mm 30mm＜Size≦52mm Pitch TPI ≦7/8in. 7/8in≦1 1/4in. 1 1/4in.≦2in. ≦0.6mm More than 40 (TPI) A type B type B type 0.6mm＜Pitch≦1.75mm 14(TPI)≦ 40(TPI) B type B type B type 12(TPI)・13(TPI) B type B type B type 2mm 11(TPI) B type B type C type 2mm＜Pitch≦5mm 5(TPI)≦ 10(TPI) B type C type C type Tolerance=15μm Tolerance=20μm Tolerance=40μm Basic Pitch Dia. Basic Pitch Dia. Basic Pitch Dia. 2. JIS Limit Thread limits of taps for metric threads : Today the thread limits of ISO2857 are specified in the main book of JIS, and those of old 1st class, 2nd class and 3rd class are specified in JIS Appendix. In the thread limits of 1st, 2nd and 3rd classes (old JIS), the pitch diameter tolerances change depending on nominal size and pitch even if the class is same. On the other hand, in the thread limit of ISO2857 (current JIS), the pitch diameter tolerance is same and only the tolerance position changes as far as the nominal size is same. The tolerance, as shown in the next picture (Page 669), is specified as X% of internal thread tolerance and it changes depending on nominal diameter and pitch. Thread classes of the main book of JIS will be said to be a system located in the middle of YAMAWA P class and old JIS class. To show clearly, Information thread limit classification is called Class 1, Class 2 and Class 3 in current JIS, and 1st class, 2nd class and3rd class in old JIS. Technical Technical-13